Electric converter



(N0 Model.) 2 Sheets-Sheet 1.

M. G. PARMER. ELECTRIC CONVERTER.

No. 448,644. Patented Mar. 24, 1891.

men STATE PATENT Orricn.

MOSES G. FARMEB, OF ELIOT, MAINE.

ELECTRIC CONVERTER.

EEGIFICATION forming part of Letters Patent No. 448,644, dated March 24-, 1891,

Application filed October 11, 1890. Serial No. 367,785. (No model.)

To aZZ whom it may concern.-

Be it known that I, MOSES G. FARMER, a citizen of the United States, residing at Eliot, in the county of York and State of Maine, have invented certain new and useful Improvements in Electric Converters; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention has reference to improvements in electrical converters 0r inductoriums for converting by induction currents of a given tension into currents of a different tension; and my improvements have special reference to the construction of the core of the converter and to the magnetic shield for confining the magnetic lines of force upon the inducing and induced coils. In apparatus of this kind the core is frequently built up of aminne of iron, separated from each other by thin layers of insulating material, such as paper, card-board, doc, and in many cases the lamina: of magnetic material are placed directly in contact with each other without the intervention of insulating material. In both constructions there is this defect, that the assembling of the lamina) which constitute the core is tedious and complicated, and in the case where insulating partitions between the laminae are used the building up of the core requires great care and nicety of manipulation. .Vhen no insulating portions are used, the rapidity of magnetization and demagnetization of the core is in a great measure lost, so that induetoriums made with such cores are very little better than if the cores were made of solid pieces. By myinvention these defects are overcome in that I retain the principle of laminating the core; but in place of the insulating material for separating the magnetic laminze I use very thin sheets of non-magnetic metal, each of which, together with two magnetic lamina: soldered or sweated to it, constitutes a core element,

and all these elements may be assembled to build up a core of any desired cross-section in an expeditious and easy manner. I have also found that the eiiiciency ofthe converter is increased when each magnetic laminae is made either shorter than the whole length of the core, or when it is made in two parts, which together have the length of the core, but are not in direct or solid contact, so that the core may be laminated not onlyin planes parallel to its axis, but also in planes at right angles thereto.

The magnetic shield which I provide I construct in two parts, closely fitting the polepieoes of the core and so shaped as to be easily mounted and dismounted. All this will more fully appear from the following detailed description, with reference to the accompanying drawings, in which- Lhave shown in Figure 1 a face view of a non-magnetic metallic lamime entering into the construction of my improved convertercore; in Fig. 2, a like view of a magnetic laminae; Figs. 3 and +1, edge views of one form of a core element and an assemblage of the same respectively in accordance with my invention. Figs. 5 and 6 are like views of another form of a core element and of an assemblage of the same. Figs. 7 and S are edge views of still another form of a core element and an assemblage of the same, respectively. Fig. 9 is a perspective view of one form of my improved converter-core. Fig. 10 is a perspective view of a converter or inductorium constructed in accordance with my invention, showing a portion of the magnetic shield broken away; and Fig. 11 is a perspective view of a cup-shaped magnetic shield.

In the construction of my improved converter-coreIuse a great number of thin sheets of non-magnetic metal, shaped as shown in Fig. 1that is to say, with a shank l and a cross-head 2 formed at each end of the shank. These non-magnetic laminae may be made of zinc, brass, copper, or other like metal, and they are covered on both sides with a thin adherent film of tin or other easily-fusible non magnetic metal. This is done by the ordinary process of tanning, and it is of no consequence whether in this process the edges of the laminae are also tinned or not, except as will be hereinafter set forth.

For each laminae of non-magnetic metal I provide two laminae of soft iron, which are also tinned on both sides, and are therefore preferably cut from the ordinary tinned sheetiron. These magnetic laminae are shaped as shown in Fig. 2-that is to say, with a shank 3 and a cross-head 4: at one end of the shank only. The shank 3 and the cross-heade have 9 9 they are bolted together.

the same width as the like elements in the non-magnetic laminae, and the length of the cross-head 4 is equal to that of the crosshead 2, while the shank of the magnetic laminae may be made either of the same length as the shank 1, as indicated in dotted lines in Fig. 2, or, by preference, it may be made only half the length of the shank of the nonmagnetic laminae, in Fig. 2.

Having provided a great number of these magnetic and non-magnetic laminae, they may be put together to form acore element in a' Variety of ways. In Fig. 3 one such core element is shown, and it will be seen that it is made of non-magnetic laminae, with two magnetic laminae applied with the ends of their short shanks toward each other on the same tinned surfaces in contact become fused or sweated together.

By reference to Figs. 1 and'2 it wil'lbe seen that in the center of each cross-head there is a perforation 5, and it will be clear that when a core element like that shown in Fig. 3 is completed the perforations inthe magnetic laminae will coincide with the perforations'in the non-magnetic laminae. If desired, these perforations may be made after the sweating together of the magnetic and nonmagnetic laminae; but under all circumstances they must be in each core element in precisely the same position in the cross-heads.

The end edges 6 of the shanks of the magnetic laminae need not be carefully made to be in close magnetic contact, and, in fact, I

have-found that these edges may with ad-' vantage be out of contact or separated from each other by a thin film of tin, which in the process of making the core element will eventually be forced between them. The long edges 7 of the cross-heads of the magnetic laminae, however, must be free from tin or any other non-magnetic substance, for reasons which will hereinafter more fully appear.

The core elements shown in Fig. 3 are assembled to form a converter core in the manner indicated in Fig. 4=that is to say, they are piled upon each other or strung upon'two bolts 8 8, by means of which and by suitable nuts As will be seen by reference to Fig. 4, the core elements are so piled upon each other that the magnetic laminae of one is separated from themagnetic laminte of the next succeeding one by a nonmagnetic laminae. When the core elements are thus assembled, the core has the shape shown in Fig. 9, the assembled cross-heads constituting the flanges lO-o'f the'cor'e 11, upon which the layers "of insulated wire of the transformer are coiled. In Fig. 10 the coils as indicated in solid lines second flange.

of insulated wire are shown applied to the core, the coarse wire 12 in this instance being shown next to the core and the fine wire 13 covering the coarse wire; but, as is well understood, this arrangement may be reversed. In Fig. 5 another form of core-unit is shown. In this case it will be seen that each unit consists, as in the construction so far described, of a lamina of non-magnetic metal and two laminae of magnetic metal; but in this case the magnetic laminae are sweated {to opposite sides on the same end of the nonmagnetic laminae. When such core elements are assembled, as indicated in Fig. 6, the group formed is substantially like that shown in Fig. 4:, except that the terminal plates show a break of continuity, which is remedied by the addition at each end of the magnetic laminae, as indicated in dotted lines at 3' 4;. I have so far described the use of magnetic laminae the shanks of which are only half as long as the shanks of the non-magnetic laminae; but, as stated above, the shanks in both laminae may have the same length, in which case the core-unit will appear as in Fig. 7, and the assemblage of the same will appear as in Fig. '8. At each end plate, therefore,

the cross-head will have a depression which may be filled out by a supplemental crosshead 4 of non-magnetic material 2', as indicated in dotted lines. In this construction the magnetic cross-heads in the alternate core-units will be missing, and I have found that the etliciency of conversion is thereby not only not impaired, but is actually improved. If so desired, the gaps between the successive cross-heads may be filled out by non-magnetic material. It will be noticed that in this construction there are between two successive non-magnetic laminae two magnetic laminae; but these two are not in magnetic contact, since the surfaces of the iron are tinned. 7e have therefore in this instance, as in the other forms described, alternate layers of iron and non-magnetic material, thesu'cc'essive laminm of non-magnetic soft iron, constructed as shown in Fig. 10 that is to say, each of a plate of iron extend- 1 ing from the middle of one flange of the core I and iucontact therewith, as indicated at 14, then bent around the edge of said flange, and extendingdown to the other flange of the core,

as indicated at 15, where it is again bent at right angles, extending tothe middle of this This band is, besides, provided with an upright flange 16 at eachend, and the two bands when assembled upon the core in'the'manner shown in Fig. 1Ov are joined by their flanges 16 and form a magnetic shield, or, more correctly speaking, a magnetic circuit, for the lines of force. This shield, therefore, being composed of two separable parts, may be slipped onto the converter when otherwise finished, and may be removed for inspection and repair.

\Vhile I use by preference the construction of magnetic shield thus described with reference to Fig. 10,1 may also use the hood or cap-shaped construction indicated in Fig. 11, which in effect is nothing but a housing of iron inclosing the converter on all sides. It is made like the construction shown in Fig. 10, in two parts, each part being provided with lugs 17 17, by means of which the said parts are coupled together. I have found, however, that a complete magnetic circuit or path for the magnetic lines of force between the poleterminals must not necessarily in close the converter upon all sides, and the construction shown in Fig. 10 being the cheaper and having the same eiiiciency as a hood or cupI use by preference a magnetic shield or circuit composed of two angular bands of soft iron.

Having fully described my invention, what I claim as new, and desire to secure by Letters Patent, is-

1. A core for an electrical converter or inductorium, composed of laminae of tinned iron with laminze of non-magnetic metal interposed between them, substantially as set forth.

2. A core element for an electrical converter or inductorium, consisting of a sheet of nonmagnetic metal having one or more laminze of iron fused to its surface or surfaces, substantially as described.

8. A core element for an electrical converter or inductorium, consisting of a thin sheet of non-magnetic metal formed with a shank and a cross-head at each end, in combination with two laminae of iron, each formed with a shank having half the length of the shank of the sheet of non-magnetic metal and a single cross-head and fused to the sheet of non-magnetic metal, substantially as set forth.

4. A core element for an electrical converter or inductorium, consisting of an I -shaped lamina of non-magnetic metal, in combination with two T-shaped laminze of magnetic metal fused to and covering the non-magnetic lamina, substantially as described.

5. In an electrical converter or ind uctorin m, the combination of a laminated core having free polar terminals with a magnetic shield composed of two flanged angle-irons closely fitting the poles of the core and each other, substantially as set forth.

In testimony whereof I have signed this specification in the presence of two subscribing witnesses.

HOSES G. FARMER.

Witnesses:

SARAH J. FARMER, FRANCIS Knnnn. 

